A new automated continuous‐flow washing system that utilizes disposable wash sets was evaluated for its efficiency in washing bloods glycerolized with equal volumes of Huggins' solution and frozen at −85 C in two‐liter bags. An initial gradient dilution with commercially available electrolyte solutions, modified by the addition of NaCl to give the desired osmolarities, was performed, followed by washing with 500 ml of 20 per cent mannitol in 0.45 per cent saline solution and 2,000 ml of the electrolyte solution. The mean RBC recovery in vitro was 84 per cent, with a range of 79 to 91. The breakdown of the 16 per cent loss was: freeze‐thaw, four per cent; dilutional step, nine per cent; washing, three per cent. The mean RBC survival in vivo with one of the solutions tested was 93 per cent, with a range of 88 to 98. This solution was modified to a final glucose concentration of 300 mg/100 ml and the pH adjusted to 7.4 with TRIS buffer. A significantly lower mean RBC survival of 88 per cent was obtained, with a range of 82 to 95. The maximum supernatant hemoglobin observed after post‐wash storage at 4 C for 24 hours was 804 mg/100 ml, and a low of 137 mg/100 ml. The final osmolarity ranged from 277 to 398 mosm/liter. The total processing time for two units is 70 minutes, of which 40 minutes is spent on the automated washing step. The system appears to be well suited for the large scale processing of frozen blood. However, further work is needed to define the optimum processing solutions particularly for the dilutional step during which time the greatest loss of RBC appears to occur. Its use for blood frozen in liquid nitrogen is under current investigation.

Whole blood was collected in increments varying from 100 g to 600 g into plastic containers intended for 450 ml collections. In order to determine the clinical usefulness of over and undercollected bloods, red blood cell survival studies were performed after 21 and 28 days of storage and in vitro measurements were performed weekly throughout the storage period. The red blood cell survival of 21-day-old CPD bloods was acceptable if as little as 300 g of blood were collected whereas a minimum of 400 g of blood was necessary to provide normal survival after 21 days storage in ACD solution. If as much as 600 g of whole blood were collected into a standard ACD or CPD blood pack, the red blood cell survival was within normal limits after 21 days of storage. These data demonstrate the limits to which over- and undercollected units can be utilized in transfusion therapy.